1. Field of the Invention
The present invention relates to a data communication apparatus and a data communication method that communicate by storing non-voice data in a voice packet, in a voice communication system that dialogues by exchanging voice packets via an IP network.
2. Description of Related Art
In recent years, so-called VoIP (Voice over Internet Protocol) communication system has rapidly become available. The VoIP dialogues by exchanging voice packets via an IP network. In addition, an IP telephone adaptor apparatus has been introduced, the apparatus enabling the continued use of an ordinary PSTN telephone in the VoIP communication system.
In addition, a data communication apparatus has become known, realizing transmission of high resolution image data for Internet facsimile apparatuses, by exchanging capability information in accordance with a mail protocol, the Internet facsimile apparatuses performing data transmission by storing image data in e-mail (see Related Art 1).
[Related Art 1]
Japanese Patent Laid Open Publication 2002-368815
Therefore, by utilizing an IP telephone adaptor apparatus similarly to a telephone, it becomes possible, in principle, to use the conventional data communication apparatus for the PSTN (e.g., facsimile apparatus) in the VoIP communication system. However, since the VoIP communication system is optimized for voice communication, various problems occur when used for facsimile communication (data communication). For example, the VoIP communication system does not retransmit data to ensure the real-time voice reproduction. Therefore, when there is an overflow within a jitter buffer, the data is destroyed. When there is an underflow, the data is interpolated based on the data immediately before. Such data destruction and interpolation would lower the communication quality for data communication, interfering an accurate data reproduction.
In order to perform data communication utilizing the VoIP communication system, the configuration of the IP telephone adaptor apparatus needs to be changed in order to be suited to data communication (to accurately reproduce data). When both caller apparatus and receiver apparatus have a function specialized for data communication, it is possible to achieve high-speed data communication with an independently set specification, without being limited to a common standard method for the VoIP communication system. This improvement would greatly enhance the convenience of the data communication apparatus.